Abstract
It is less than a decade since the first scientifically valid study of a possible link between blood groups and schizophrenia was published. The results of the few articles which have appeared since then are contradictory and do not clarify the original problem. This might be due to insufficient evidence for diagnosing schizophrenia and to a lack of homogeneity in the patient population. To remedy this situation in the present study only those patients whose symptoms were characteristic of schizophrenia according to the criteria of either E. Bleuler or K. Schneider were accepted. Our results indicate no correlation between blood group and schizophrenia. Until schizophrenia can be diagnosed with the same certainty as can ABO blood groups, the relationship between them cannot be scientifically established.